Feeding of liquid to gas liquid chromatographic columns

ABSTRACT

AN INJECTION DEVICE FOR TRANSFERRING AN ACCURATELY KNOWN QUANITY OF A LIQUID TO A CHROMATOGRAPHIC COLUMN FOR ANALYSIS WHICH COMPRISES A SLIDABLE MEMBER FOR CARRYING A CAPILLARY TUBE BETWEEN A LOADING STATION, AT WHICH THE TUBE CONTAINING THE LIQUID IS INTRODUCED INTO THE SLIDABLE MEMBER, AND AN INJECTION STATION AT WHICH THE TUBE IS IN COMMUNICATION WITH A CARRIER GAS STREAM WHICH CONVEYS THE LIQUID INTO THE COLUMN. THE SLIDABLE MEMBER HAS TWO PASSAGES THERETHROUGH, ONE CARRYING THE CAPILLARY TUBE AND THE OTHER TO ALLOW CARRIER GAS TO FLOW THROUGH THE MEMBER WHEN THE SAID ONE PASSAGE IS AT THE LOADING STATION. A HOLDING MEANS IS PROVIDED AT THE LOADING STATION TO HOLD THE CAPILLARY TUBE TEMPORARILY UNTIL THE SLIDABLE MEMBER IS MOVED.

Feb. 2, 1971 x w. o. EVANS 3,559,454

FEEDING OF LIQUID To GAS LIQUID CHROMATOGRAPHIC COLUMNS Filed Nov. '26, 1968 I Fig.1. 12

United States Patent US. Cl. 7323.1 2 Claims ABSTRACT OF THE DISCLOSURE An injection device for transferring an accurately known quantity of a liquid to a chromatographic column for analysis which comprises a slidable member for carrying a capillary tube between a loading station, at which the tube containing the liquid is introduced into the slidable member, and an injection station at which the tube is in communication with a carrier gas stream which conveys the liquid into the column. The slidable member has two passages therethrough, one carrying the capillary tube and the other to allow carrier gas to flow through the member when the said one passage is at the loading station. A holding means is provided at the loading station to hold the capillary tube temporarily until the slidable member is moved.

The present invention relates to devices for gas liquid chromatography for injecting a sample into the chromatographic column.

One of the major problems in bringing about an efficient use of gas chromatographic separations is the transfer of a known quantity of a sample to the chromatographic column. This is due to the difliculty of inserting a known quantity of liquid from a sample holder directly into the stream of gas which flows into and through a chromatographic column. Broadly speaking, two main methods are employed. One is to use a hypodermic syringe from which the liquid is injected into the gas system by penetrating a sealf-sealing rubber disc with the hypodermic needle. However, this method does not achieve great accuracy. The second method is to enclose a volume of the liquid sample in a capillary tube which is transferred into the gas system by a somewhat complicated mechanism of injection valves. The present invention relates to an improvement in the injection of samples from capillary tubes.

The invention consists in an injection device for gas liquid chromatography which comprises a support, having two apertures, one of which is adapted to be located at an injection station in line between a gas entry conduit and a conduit leading to a chromatographic column, and the other of which is adapted to receive a capillary tube containing a sample of liquid which tube is loaded thereinto at a loading station, said support being movable to transfer said capillary tube from said loading station to said injection station to allow gas from said gas entry conduit to pass through said capillary tube into said chromatographic column, entraining the liquid contained in said capillary tube.

Preferably, the support is in the form of a slide membet and holding means. are provided at the loading station to hold the capillary tube temporarily until the slide member is moved, when the tube is disengaged from the holding means by the sliding action.

The holding means may comprise a magnetic member in which case the capillary tube is mounted in a holder of ferromagnetic material.

One embodiment of the invention is illustrated in the 3,559,454 Patented Feb. 2, 1971 accompanying drawing, in which FIG. 1 is a sectional side elevation of an injection device, and FIG. 2 is an enlarged view of part of the loading station. FIG. 1 shows a support 1 in the form of a slide member having two transverse bores 2 and 3, and slidable between upper and lower plates 5 and 4 by the use of a handle member 9.

The upper plate is provided with a gas entry conduit 6 connectable to a suitable source of carrier gas (not shown) and the lower plate has a conduit 7 leading to a chromatographic column (not shown). The bore 2 is a fine bore and in the position of the slide member 1 shown, the bore 2 communicates both with the conduit 6 and with the conduit 7, suitable gas seals being provided at 8.

The bore 3 is larger than the bore 2 and is intended to receive a capillary tube 10 mounted in a holder 11 of ferromagnetic material. In the position shown, the tube 10 is at a loading station, and is held in position by a magnetic rod 12 supported by a tubular extension 13 from the plate 5.

Movement of the slide member 1 transfers the holder 11 with the tube 10 from the loading station to the injection station where the slide member is stopped by shutting a stop 14 between plates 5 and 4, to allow gas from the source to pass through the tube 10 to entrain the liquid sample in the tube and convey it into the column.

To reload, the slide member 1 is returned to its initial position, the rod 12 is axially withdrawn from the extension 13 and another sample tube is attached to the lower end thereof and is lowered to a position within the bore 3.

It will be apparent that the foregoing description is only by way of example and that various modifications may be made to the specific details referred to without in any way departing from the scope of the invention.

I claim:

1. An injection device for gas liquid chromatography which comprises a support, having two apertures, one of which is adapted to be located at an injection station in line between a gas entry conduit and a conduit leading to a. chromatographic column, and the other of which is adapted to receive a capillary tube containing a sample of liquid, said capillary tube being loaded thereinto at a loading station, said support being in the form of a slide member and holding means provided at the loading station to hold the capillary tube temporarily until said slide member is moved, whereupon said tube becomes disengaged from the holding means by the sliding action and becomes transferred to said injection station to allow gas from said gas entry conduit to pass through said capillary tube into said chromatographic column, thereby entraining the liquid contained in said capillary tube.

2. An injection device for gas liquid chromatography as claimed in claim 1, wherein the holding means comprises a magnetic member and the capillary tube is mounted in a holder of ferromagnetic material.

References Cited UNITED STATES PATENTS 3,000,218 9/1961 Marks et a1 73422(GC) 3,100,984 8/1963 Martin 73422(GC) 3,118,300 1/1964 Jenkins 73422(GC)X 3,160,015 12/1964 Charlton et al. 73422 (GC) 3,205,711 9/1965 Harris 73422(GC) LOUIS R. PRINCE, Primary Examiner H. C. POST III, Assistant Examiner US. Cl. X.R. 73422 

